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出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2016/08/03 21:37:12」(JST)
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Prostanoids are a subclass of eicosanoids consisting of the prostaglandins (mediators of inflammatory and anaphylactic reactions), the thromboxanes (mediators of vasoconstriction), and the prostacyclins (active in the resolution phase of inflammation.)
Main articles: Prostaglandin, Prostacyclin, and Thromboxane
Biosynthesis
Prostaglandin H2
PGD synthase
PGD2
PGJ2
PGE
synthase
PGE2
PGA2
PGB2
Prostacyclin synthase
PGI2
6-keto-PGFα
PGE
9-ketoreductase
PGF2
Thromboxane-A
synthase
TXA2
Cyclooxygenase (COX) catalyzes the conversion of the free essential fatty acids to prostanoids by a two-step process. In the first step, two molecules of O2 are added as two peroxide linkages and a 5-member carbon ring is forged near the middle of the fatty acid chain. This forms the short-lived, unstable intermediate Prostaglandin G (PGG). One of the peroxide linkages sheds a single oxygen, forming PGH. (See diagrams and more detail at Cyclooxygenase). All other prostanoids originate from PGH (as PGH1, PGH2, or PGH3).
The image at right shows how PGH2 (derived from Arachidonic acid) is converted:
- By PGE synthetase into PGE (which in turn is converted into PGF)
- By PGD synthetase into PGD
- By Prostacyclin synthase into prostacyclin (PGI2)
- By Thromboxane synthase into thromboxanes
The three classes of prostanoids have distinctive rings in the center of the molecule. They differ in their structures. The PGH compounds (parents to all the rest) have a 5-carbon ring, bridged by two oxygens (a peroxide.) The derived prostaglandins contain a single, unsaturated 5-carbon ring. In prostacyclins, this ring is conjoined to another oxygen-containing ring. In thromboxanes the ring becomes a 6-member ring with one oxygen.
Production of PGE2 in bacterial and viral infections appear to be stimulated by certain cytokines, e.g., interleukin-1.[1]
See also
- Essential fatty acid
- Isoprostane
References
- ^ University of Kansas Medical Center (2004). "Eicosanoids and Inflammation" (PDF). Retrieved 2007-01-05. [dead link]
Eicosanoids
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|
Precursor |
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Prostanoids |
Prostaglandins (PG) |
Precursor |
|
|
Active |
D/J |
|
|
E/F |
|
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I |
- I2 (Prostacyclin/Epoprostenol):
|
|
|
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Thromboxanes (TX) |
|
|
|
Leukotrienes (LT) |
Precursor |
- Arachidonic acid 5-hydroperoxide
|
|
Initial |
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SRS-A |
|
|
|
Eoxins (EX) |
Precursor |
- Arachidonic acid 15-hydroperoxide
|
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Eoxins |
|
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Nonclassic |
- Lipoxins (LX) (A4, B4)
- Virodhamine
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By function |
- vasoconstriction
- vasodilation
- platelets: induce
- inhibit
- leukocytes: induce
- inhibit
- labor stimulation:
- PGE2 (Dinoprostone)
- PGF2α (Dinoprost)
|
Prostanoid signaling
|
|
Receptor
(ligands) |
|
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Enzyme
(inhibitors) |
COX (PTGS) |
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PGD2 synthase |
- Retinoids
- Selenium (selenium tetrachloride, sodium selenite, selenium disulfide)
|
|
PGE synthase |
HQL-79
|
|
PGF synthase |
Bimatoprost
|
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PGI2 synthase |
Tranylcypromine
|
|
TXA synthase |
- Camonagrel
- Dazmegrel
- Dazoxiben
- Furegrelate
- Isbogrel
- Midazogrel
- Nafagrel
- Nicogrelate
- Ozagrel
- Picotamide
- Pirmagrel
- Ridogrel
- Rolafagrel
- Samixogrel
- Terbogrel
- U63557A
|
|
|
Others |
- Precursors: Linoleic acid
- γ-Linolenic acid (gamolenic acid)
- Dihomo-γ-linolenic acid
- Diacylglycerol
- Arachidonic acid
- Prostaglandin G2
- Prostaglandin H2
|
|
See also: Leukotrienergics
|
UpToDate Contents
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English Journal
- Evidence that PGE2 in the dorsal and median raphe nuclei is involved in LPS-induced anorexia in rats.
- Kopf BS, Langhans W, Geary N, Hrupka B, Asarian L.AbstractAnorexia is an element of the acute-phase immune response. Its mechanisms remain poorly understood. Activation of inducible cyclooxygenase-2 (COX-2) in blood-brain-barrier endothelial cells and subsequent release of prostaglandins (e.g., prostaglandin E2, PGE2) may be involved. Therefore, we sought to relate the effects of prostaglandins on the anorexia following gram-negative bacterial lipopolysaccharide treatment (LPS) to neural activity in the dorsal and median raphe nuclei (DRN and MnR) in rats. COX-2 antagonist (NS-398, 10mg/kg; IP) administration prior to LPS (100μg/kg; IP) prevented anorexia and reduced c-Fos expression the DRN, MnR, nucleus tractus solitarii and several related forebrain areas. These data indicate that COX-2-mediated prostaglandin synthesis is necessary for LPS anorexia and much of the initial LPS-induced neural activation. Injection of NS-398 into the DRN and MnR (1ng/site) attenuated LPS-induced anorexia to nearly the same extent as IP NS-398, suggesting that prostaglandin signaling in these areas is necessary for LPS anorexia. Because the DRN and MnR are sources of major serotonergic projections to the forebrain, these data suggest that serotonergic neurons originating in the midbrain raphe play an important role in acute-phase response anorexia.
- Pharmacology, biochemistry, and behavior.Pharmacol Biochem Behav.2011 Sep;99(3):437-43. Epub 2011 Apr 17.
- Anorexia is an element of the acute-phase immune response. Its mechanisms remain poorly understood. Activation of inducible cyclooxygenase-2 (COX-2) in blood-brain-barrier endothelial cells and subsequent release of prostaglandins (e.g., prostaglandin E2, PGE2) may be involved. Therefore, we sought
- PMID 21527272
- A profile of NSAID-targeted arachidonic acid metabolisms in human embryonic stem cells (hESCs): Implication of the negative effects of NSAIDs on heart tissue regeneration.
- Chillar A, So SP, Ruan CH, Shelat H, Geng YJ, Ruan KH.SourceCenter for Experimental Therapeutics and Pharmacoinformatics, Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas, United States.
- International journal of cardiology.Int J Cardiol.2011 Aug 4;150(3):253-9. Epub 2010 May 7.
- INTRODUCTION: An emerging technology using human embryonic stem cells (hESCs) to regenerate infarcted heart tissue has been underdeveloped. However, because non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin, are taken during the infarction, it becomes critical to know whether the NSAID
- PMID 20451268
Japanese Journal
- Honda Tetsuya,Kabashima Kenji
- Allergology International 64(1), 11-16, 2015
- … Prostanoids, which include prostaglandin and thromboxane, are metabolites of arachidonic acid released in various pathophysiological conditions. … Here, we review the recent findings on the roles of prostanoids in allergy, especially focusing on atopic dermatitis and asthma. …
- NAID 130004873121
- Roles of Prostanoids in Regulation of Angiogenesis and Lymphatic Tissue Remodeling
- Majima Masataka
- Microvascular Reviews and Communications 7(1), 31-31, 2014
- Inflammation influences the pathogenesis of cancers by induction of genome damage, proliferation in stromal cells, and generation of inflammatory mediators. Angiogenesis is also a critical step for de …
- NAID 130004678469
- Roles of eicosanoids in pulmonary fibrosis
- Oga Toru,Handa Tomohiro,Mishima Michiaki,Chin Kazuo,Narumiya Shuh
- Inflammation and Regeneration 33(2), 109-113, 2013
- … Mice lacking cytosolic phospholipase A<SUB>2</SUB>, a key enzyme triggering the production of arachidonic acid metabolites such as eicosanoids including prostanoids and leukotrienes, did not develop bleomycin-induced pulmonary fibrosis, indicating that arachidonic acid metabolites play an important role in the pathogenesis of pulmonary fibrosis. …
- NAID 130004943838
Related Links
- PROSTANOIDS AND RELATED COMPOUNDS A large number of fatty acid derivatives often present in tiny concentrations were discovered to have profound effects on cellular physiological or pathophysiological reactions. Because of ...
- Cyclooxygenase (COX) catalyzes the conversion of the free essential fatty acids to prostanoids by a two-step process. In the first step, two molecules of O 2 are added as two peroxide linkages and a 5-member carbon ring is forged ...
Related Pictures